1. Field of the Invention
The present invention relates to a method for producing a foam mold, and more precisely, it relates to an improved method for producing a foam product, in which a core material having an opening is set in a molding die, so that a foaming resin material is poured therein to produce a foam mold.
2. Description of Related Art
For instance, interior mold products, such as instrument panel, arm rest, knee protector, door panel etc. in an automobile are made of a skin material and a predetermined shape of core material, which are set in a molding die, so that a foaming agent, such as a polyurethane resin is poured therein to produce a foam product (mold).
Such foam products usually have complex shapes and different sizes of openings, depending on the functions thereof and in connection with elements associated therewith.
Upon molding, as shown in FIG. 5, the foaming material enters the back side of the core material 10 through the opening 11 thereof, so that the foaming material remains therein to form a burr or flash applied to a product or a molding surface of the molding die. The burr or flash damages both the molding die and the products, and sometimes causes a problem by the occurrence of a defect or a cavity in the products. In FIG. 5, numeral 19 designates a skin of a product, 41 a lower molding die, 42 an upper molding die, and 43 a cavity, respectively.
To eliminate these drawbacks, the inventors of the present invention tried to provide an improved foaming process in which a predetermined shape of seal member 15 made of a slab of polyurethane foam is first adhered to the core material 10 to cover the opening 11 therein, and then the foaming resin material is poured in the molding die, as shown in FIG. 6. Since the seal member 15 which is made of a slab of polyurethane foam has air permeability, the gas which is produced during foaming and any air remaining in the molding die permeate through the seal member 15. However, the inventors found that the pressure of the foaming resin material during foaming caused the foaming material to pass through the sealing member 15 and the opening 11 of the core material 10, so that the foaming material entered the back side of the core material 10 anyway and penetrated into the upper molding die 42. This is because no counter pressure is applied to the lower molding die 41 from the upper molding die at the opening 11 of the core material 10.